Stoker furnace



Aprillz, 1938. J., H. LAWRENCE 2,113,891

1 vSTOKER FURNACE Filed March 24, 1936 4 Sheets-Sheet 1 www ATTO R N EYS sToKER FURNACE April 112, 193s. J. H. LAWRENCE 'y 2,113,891

Filed March 24, 19:56 4 sheets-sheet 2 INVENTOR figg/vfill/:Wv ENCE.

MAM-foreman APl-l2, 1938. '.J. H. LAWRENCE 113,891

sToKER FUNACE 4 FiIed March 24, 1936 4Sheets-Sheet 4 INVENTOR ATTO R NEYS Perenfed Ape. 12, 193sv 4PATENT OFFICE r anassi s'roxna nommer.

John H. Lawrence, Bronxville, N. Y., assigner to Metropolitan Engineering Company, Brooklyn, NaY., 'a corporation of New York l Application Maren 24, 1936,. serial No. 70,5s6

9 claims. '(cl. 12H) and of the stoker mechanism, as hereinafter de.

scribed in detail.

The accompanying drawings illustrate embodiments of the invention.

l Fig. 1 is a longitudinal section of a Stoker r'ed boiler. Fig. 2 is a perspective sectional view of the grate and adjacent parts. Fig. 2 is a vertical cross section throughthe fuel feeding and airv feeding parts of the grate, taken on the lineA 2l 1 of Fig. 2. Fig. 3 is a section through one of the air feeding channels. Figsj. 5, 6'and 7 are sideelevations illustrating alternative designs of tubes forming parts of the air feed sections. Fig. 8

is a plan of the tube shown in Fig. 7. Figs. 9, 10 and 11 are views similar to Fig. 3. showing alternative constructions of the air feed sections.

' In Fig. 1 the upper part -of the boiler carries a lower bank of tubes and an upper bank 2 with baflies 3 and 4 by which the hot gases are directed over the tubes and finally out by the smoke outlet 5. The'tubes at opposite ends run into headers 6, 1, 8 and 9; the headers on the lower ends being fed lbv water coming down from the drum I0. This upper structure is carried in a casing Il, I2.

` 30 Numerous other arrangements of water tubes and sm'okevpassages are known and may beV utilized with this invention. i L

The combustion chamber of the furnace I3 is enclosed within walls I4, i5 which in the case 35 illustrated .are lined with upright tubes I6 and |1 which may be connected into-the main or accessory circulation` of the boiler in .various known Ways.

In the lower part of the furnace is the grate-to which coal is fed from a hopper I8 at the front, Athegrate being inclined downward toward the back to an ash discharge chute I9 and disposed of in any usual Way. An air chamber 2|) feeds air through dampers 2| to the space beneath the grate; the air being heated generally-.to a'high temperature in advance so'as to secure the morel intense combustion. 'Ihe grate is composed of longitudinal plates 22 50 which divide the entirearea into sections or retorts. In the alterna-tive spaces between these nating with the air feed sections, as shown in Hg. 28.

Referring to Fig. 2 there are xed plates 23 .extending across from -one longitudinal plate 22 to thev next; the plates 23 being spaced apart 5 y alongthe length of the grate. In the intervals between the fixed plates 23 are the longitudinally reciprocable plates 24 which are attached by rocker arms 25 to rods 26 each of which is connected by a'link 21 toa rod 23 running through a l0 stufling box 29 in the front wall and connected-at its outer end by a link 30 to a rocking plate 3|. At the lower end of the grate is a special plate or section 32 which is similarly connected by a rocker arm 33, link 34, rod 35 and link 36 to the 15 rocker 3| at the front. The rocker 3| at its -upper end engages a plunger 31 and reciprocates bedv of fuel through a special cooling structure. 2-5l As illustrated, the closed sections of the grate are comparatively narrow so that the air will be 'sufficiently distributed by its passage through the alternative cooled spaces; but supplementary air them'forpassage of the air. i

In Fig. 3 a single tube 40, such as-an ordinary three-inch or four-inch seamless steel boiler tube, for example, may be provided with projections 4| extending outward from. diametrically opposite -40 points, and resting on the walls 22 of the air retort. Each of vthefprojections is separately welded to the tube so `as to ensure a good heatconducting contact and they are spaced apart sufliciently to avoid interference with each other; 445

and close enough to secure an extensive area and an intimate air-contact.

By the separate application of the projections we secure a structure similar to a 'continuous ln with openings through it, butV with the advantage that the tubes and fins are 'not subjected vto any excessive strains under heat ofthe welding operation.v The rigid union of the fins to their tube i not only permits them to support the tube in correct position but also maintains a good heat con- Water circulates through the tubes and prevents l the overheating and undue softening of the projections. It also protects .the adjacent parts of the grate from overheating while permitting an extremely high temperature in the combustionl air fed to the furnace and a high rate of combustion.

It also tends to prevent or diminish the accumulation of fused ash on the coal feeding sections of the grate. Such an accumulation, in previous designs, has required an increasing of power for driving the stoker and has even partly cut ofi' the flow of air through the grate at times.

According to Fig. 1 the water tubes 4l onthe grate are continuatio'us of some of the tubes Il which extend down the inner face of the front wall I4 of the furnace. However, these tubes lll may be fed from a separate header 42, as. shown in Fig. 2, located on the outside of the front wall just above the coal hopper I3.

The. tu end ofthe grate pass down as at Fig. 1, along the wall of the ash pit or passageway I9=so as to provide a cooled water wall therefor. `The projections ll are not necessary in this part of the tubular structure. I

Various connections for providing and taking away the water from the tubes may be arranged. According to Fig. 1 there is a header 4I connected to they lower ends of all the tubes 43. Some of these tubes turn back at the end of the grate, as indicated at 44, and lead toa header the lother tubes leading up to'connect with the tubes v II, previously referred to.

According to Fig-.2 the lower ends of the tube sections 43 run out of a bottom header and runat their upper ends into a header l2.' Generally the heat thus applied to the water is utilized by connecting the headers into `the desired part of the boiler circulation, whether for steam generation or for superheating of the steamor preheating of the water.

v 'I'he projections Il, previously referred to, are

'the axis of the tube. In that case the.air is, forced with a somewhat greater pressure against the faces ofthe projections so as to secure a better' cooling effect. I.

In Fig. 6 vthere are shown projections Il which are jals'o oblique and, in fact, have their wider' faces nearly parallel with the direction of the axis.'`

In Figs. 7 and 8 similar projections l! are illusy trated but having their inner portions l of retube itself may be 0i' multiple form,v that is with morethan one passage for the water. The projections may be of various forms besides those illustrated. And the projections instead of being diametrically opposite may be applied tangentiallyto the tube asin Figs. 9, and 11.

According to Fig. 9 the projections (which in cross-section may be of any of the shapes Previously referred to) are formed of a single bar Il "weldedt its center t0 the tube and extending' 1fre over the side plates 22 of the retort.

Fig. 10 illustrates a similar construction,

40 after passing beyond the lowerA ing only in that the projections 52 are arched for stinness. In both Flgsf9 and 10 the tube is'below so asto receivethefirst blast of hot air; and the portions of the bar which overlie the tube, in effect thicken the wall of the tube at the top where it is most liable to b e burned out and abraded by the hot traveling fuel bed. In Fig. 1l the projections 53 are in the form of a single bar welded tangentially tothe tube 49 but this tubular unit is supported on the side platesl 22 with the tube above the projections and, therefore, closer to the' bed.of burning Yfueland farther along in the path l side of the tube, or of that portion of the length of the tube which is closest to the re. Such tubular units of general application are coveredseparately in a divisional case, No. 119.539, iiled January 8, 1937.

InA the particular case illustrated, where the tube is used as part of the grate, it is exposed to these extreme conditions along 'its whole length and'cons equent1yr/the metallicA projections or xtensions are to be provided along the whole length might not be necessary.'

What I claim is- 1. A furnace having a oor for a bed of fuel with air channels along Said floor, parts of the floor comprising. tubes for circulating la cooling medium,l said tubes-ihaving longitudinal fins ,united thereto and overlying said air channels,

"as illustrated in Fig. 1. In Iother locations this said iins being in the form of numerous small segments welded separately to the* tube with spaces between them for the passage of air to the 2. A furnace having a floor for a bed of 4fuel with air channels along saidfloor, parts of the iioor comprising tubes for circulating acooling medium, said tubes having longitudinal ilns united thereto and overlying said air channels, said ns being in the form of numerous small segments weldedseparately to the tn be with spaces between them for the passage of air to the fuel bed, said segments'over-lapping one another horizontally. v

3. A furnace having'a floor for a bed of fuel, with air channels along said floor, parts of the iioor comprising-tubular units each consisting of a tube forcirculating 'a cooling medium and having oppositelyextending fins united rigidly and permanently thereto with a good heat-conducting joint thereto, each such unit spanning one of the air channels and the fins having numerous closely spaced openings for the passage of air to the fuel l 4. A furnacenhavin'g` a stoker comprising a number of parallel reciprocating sections for advancing the coal, between which are tuyres for feedingv the air for combustion, said tuyres each comprising side walls and a tubular unit supported thereon comprising a tube for circulatingV a cooling medium and iinsunited rigidly and permanently thereto with a vgood heat-conducting joint to the tube and having openings through which air passesfa'gainst vthe tubes to the ciprocating sections for advancing the coal between which are tuyres for feeding the air for combustion, said tuyres each comprising side -walls and a tubulanunit supported thereon comn prising a, tube for circulating a cooling medium and iins-in the form of numerous small segments welded separately to the tube and having transverse openings between them through which air passes to the fuel bed.

6. A tuyre for stokers comprising side walls and a top comprising a tubular unit, said unit comprising a tube for circulating a cooling medium and fins in the form of numerous small segments welded'separately thereto and having transverse openings between them through which air can pass to the fuel bed.

'7. A furnace having a floor for a bed of fuel with air channels along said floor, parts of the floor comprising tubes for circulating a cooling medium said tubes having longitudinal iins united rigidly and permanently thereto with a good -heat conducting joint and overlying 'said air channels with numerous closely spaced transverse openings through each' oi said ns adapted to cause the passage of sir against the tubes and through 'said openings to the fuel bed.

8. A furnace having a fioor'ior a bed of fuel with air channels along said iloor, parts oi the oor comprising tubes for circuiating a-cooling medium said tubes having longitudinal iins united rigidly and permanently thereto with a good heat conducting Joint and overlying said air channels with numerous Iclosely spaced transverse openings through each of said iins adapted to cause the passage of air against the tubes and through said openings to the fuel bed and said fins overlying said tubes so as to .thicken their walls at the top.v

9. A furnace having a oor for a bed of fuel with air channels along said iioor, parts of the floor comprising tubes for circulating a cooling medium, said tubes having longitudinal ns united thereto and overlying said air channels with numerous closely spaced openings through said fins for the passage of air to the iuel bed, said finned tubes being supported with freedom ci movement relatively to the walls of said air channels.

' JOHN H. LAWRENCE. 

